Dry
roast coriander seeds, jeera, sesame seeds, black peppercorns, cinnamon
stick, cloves and fennel seeds in a skillet till they are fragrant and
roasted fine, about 1-2 mins. Set it aside to cool.Heat oil in a
same pan and roast finely sliced onion, garlic and coriander leaves
till they are nicely browned and crisp. Set them aside to cool
completely.Now grind all these ingredients to fine powder. Add red chilli powder to the ground spice powder and mix them well.Cool and store this spice powder in an air-tight container in the refrigerator.

Note:

Since
the spice powder is made using fresh ingredients like onion, garlic and
coriander leaves, make sure that they are nicely browned (but not
burnt) and dry. Or else the spice powder will have shorter shelf life.